Essendon under investigation for supplement usage

The controversial fitness regime that helped ruin Essendon's AFL season last year could now bring the club to its knees.

Ten days before Essendon's first NAB Cup match, they announced a joint investigation by the Australian Sports Anti-Doping Authority (ASADA) and the league's integrity unit.

The investigation will look into unnamed supplements that the club gave to players.

ASADA's involvement raises the worst-case scenario for the club and the AFL that Essendon players took substances that are banned under the World Anti-Doping Agency (WADA) code.

If that has happened, it will be one of the biggest crises in AFL history.

Late on Tuesday, reports emerged that the man in charge of the Bombers' fitness program, Dean Robinson - known around the league by his nickname "The Weapon" - had been stood down by the club pending the outcome of the investigation.

Essendon's stunning revelation came after months of rumours surrounding supplement use by their players.

"We want to get this investigation started. We want to get it done. We want to come out with a clean bill of health.

"We want to move on with the footy season."

Evans described the issue as a minefield, while Hird admitted the potential scandal had blindsided him.

"The supplements our players were given, in my opinion and my knowledge, were all approved and within the regulations we all play the game by," Hird said.

Late on Tuesday, Geelong released a statement confirming an individual involved with Essendon's fitness during the period under investigation had previously worked for the Cats.

"Whilst we have no evidence or information that this individual acted in an improper manner during his employment at the Geelong Football Club, we are ready to co-operate fully with the investigation," the club said in the statement.

Gold Coast AFL released a similar statement saying that an individual involved at Essendon had worked "worked briefly" for the Suns, and that the club had no knowledge or evidence of improper actions by the person while at Gold Coast.

The statement said the club was also ready to co-operate fully with the investigation.

The AFL Players' Association also released a statement saying that if information had raised concerns over the integrity of Essendon's fitness program, then the AFLPA considered the referral to the AFL and ASADA "entirely appropriate".

"Clubs providing players with supplements and directions as to their players' training requirements have a significant responsibility and in our view, any concerns regarding the nature of such directions ought to be treated with the utmost seriousness," AFLPA chief executive Matt Finnis said.